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WCDMA Idle Mode Behaviour Huawei

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WCDMA IDLE MODE BEHAVIOUR HUAWEI
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Page 1: WCDMA Idle Mode Behaviour Huawei

WCDMA IDLE MODE BEHAVIOUR

HUAWEI

Page 2: WCDMA Idle Mode Behaviour Huawei

IDLE MODE

• PLMN Selection• Cell Selection• Cell Reselection• Location Registration• Paging Reception• System Information Reception

Page 3: WCDMA Idle Mode Behaviour Huawei

PLMN Selection

At switch-on, or after lack of coverage UE will select a PLMN. The PLMN selection procedure is used for finding a suitable PLMN.

There are two modes of PLMN selection:

• Automatic selection:The UE automatically selects a PLMN according to the priority

order.

• Manual selection:The UE shows all available PLMNs to the subscriber. The

subscriber then selects a PLMN.

Page 4: WCDMA Idle Mode Behaviour Huawei

Automatic PLMN Selection

In automatic PLMN selection UE can select a PLMN from the Home PLMNs (HPLMNs) and roam in the Visited PLMN (VPLMN).

• The MCC and MNC in the PLMN identity of the HPLMN match the MCC and MNC in the IMSI of the UE.

To select a PLMN from the HPLMNs:• The UE maintains a list of allowed and available PLMNs in

priority order. When selecting a PLMN, the UE searches for the PLMNs from the highest priority to the lowest.

Page 5: WCDMA Idle Mode Behaviour Huawei

Roaming in the VPLMNIf a UE stays in a VPLMN, it regularly searches for the HPLMN and

higher-priority PLMNs for better services.

• For this purpose, a value of T minutes may be stored in the SIM. Either T is in the range 6 minutes to 8 hours in 6-minute steps or T indicates that no periodic attempts shall be made. If no value is stored in the SIM, a default value of 60 minutes is used.

• After the UE is switched on, a period of at least two minutes and at most T minutes shall elapse before the first attempt is made.

• Periodic attempts shall be performed only by the UE in idle mode.

Page 6: WCDMA Idle Mode Behaviour Huawei

Manual PLMN Selection

• The UE maintains a list of allowed and available PLMNs in priority order. When selecting a PLMN, the UE indicates the list to the subscriber who will select a PLMN, and then camps on the selected PLMN.

Page 7: WCDMA Idle Mode Behaviour Huawei

Cell Selection

• When the PLMN is selected and the UE is in idle mode, the UE starts to select a cell that belongs to the selected PLMN to camp on and to obtain normal services.

Page 8: WCDMA Idle Mode Behaviour Huawei
Page 9: WCDMA Idle Mode Behaviour Huawei

Cell Selection• Camped normally: The UE obtains normal services.

• Connected mode: After RRC connection setup, the UE changes from the idle mode to the connected mode (CELL_DCH, CELL_FACH etc.)

• Any cell selection: The UE attempts to find an acceptable cell of any PLMN to camp on.

• Camped on any cell: The UE obtains limited services and selects a cell through cell selection or reselection. In this case, the PLMN identity is not considered.

Page 10: WCDMA Idle Mode Behaviour Huawei

Initial cell selection

• If no cell information is stored for the PLMN, the UE starts the initial cell selection. For this procedure, the UE need not know in advance which Radio Frequency (RF) channels are UTRA bearers. The UE scans all RF channels in the UTRA band according to its capabilities to find a suitable cell of the selected PLMN

Page 11: WCDMA Idle Mode Behaviour Huawei

Stored information cell selection

• For this procedure,UE knows the carrier frequencies that have previously been used. After this procedure is started, the UE selects a suitable cell if any. Otherwise, the initial cell selection procedure is triggered.

Page 12: WCDMA Idle Mode Behaviour Huawei

Suitable cell

Suitable cell is the cell that the UE may camp on to obtain normal services.

• When returning to the idle mode from the connected mode, the UE shall select a suitable cell to camp on. Candidate cells for this selection are the cells used immediately before the UE leaves the connected mode.

Page 13: WCDMA Idle Mode Behaviour Huawei

Acceptable cell

• An acceptable cell is the cell that the UE may camp on to obtain limited services. For example, the UE may originate emergency calls.

• When returning to the idle mode after an emergency call on any PLMN, the UE shall select an acceptable cell to camp on. Candidate cells for this selection are the cells used immediately before the UE leaves the connected mode.

Page 14: WCDMA Idle Mode Behaviour Huawei

Cell Selection Criteria

The cell selection criterion S is fulfilled when:• Srxlev > 0 and • Squal > 0where• Squal = Qqualmeas – Qqualmin

• Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

Page 15: WCDMA Idle Mode Behaviour Huawei

Cell Selection

• Pcompensation =Max (UE_TXPWR_MAX_RACH – P_MAX, 0) (dBm)Where

• UE_TXPWR_MAX_RACH: MaxAllowedUlTxPower

• P_MAX: maximum RF output power of the UE

Page 16: WCDMA Idle Mode Behaviour Huawei

Cell Reselection

• The signal strength of both serving cell and neighboring cells varies with the movement of a UE and so the UE needs to select the most suitable cell to camp on. This process is called cell reselection. The cell reselection involves three parts:

• cell reselection process• measurement start criteria• cell reselection criteria

Page 17: WCDMA Idle Mode Behaviour Huawei

Cell Reselection Process• The cell reselection process is as follows:• 1. The UE calculates the cell SX according to the following formulas:• Squal = Qqualmeas - Qqualmin• Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation

• 2. The UE decides whether to start the intra-frequency or inter-frequency measurement according to the measurement start criteria.

• 3. The cells are queued according to the measurement results.• 4. The UE selects a suitable cell to camp on according to the cell

reselection criteria

Page 18: WCDMA Idle Mode Behaviour Huawei

Measurement Start Criteria

• If Squal > Sintrasearch, the UE need not start the intra-frequency measurement.

• If Squal ≤ Sintrasearch, the UE need start the intra-frequency measurement.

• – If system messages do not contain Sintrasearch, the UE always need start the intrafrequency measurement

Page 19: WCDMA Idle Mode Behaviour Huawei

Inter-frequency & Inter-RAT measurement

• If Squal > Sintersearch, the UE need not start the inter-frequency measurement.

• If Squal ≤ Sintersearch, the UE need start the inter-frequency measurement.

• If system messages do not contain Sintersearch, the UE always need start the interfrequency measurement.

• If Squal > SsearchRATm, the UE need not start the inter-RAT measurement.

• If Squal ≤ SsearchRATm, the UE need start the inter-RAT measurement.• If system messages do not contain SsearchRATm, the UE always need

start the inter-RAT measurement.

Page 20: WCDMA Idle Mode Behaviour Huawei

Cell Reselection Criteria

TEMP_OFFSETn is used as an offset to the R criteria for the duration of PENALTY_TIME after a timer Tn is started for that neighboring cell.

TEMP_OFFSETn and PENALTY_TIMEn are only applicable when the system information indicates that the HCS is enabled.

Page 21: WCDMA Idle Mode Behaviour Huawei

• Qhysts IdleQhyst1s• IdleQhyst2s

• Qoffsets• IdleQoffset1sn• IdleQoffset2sn

Page 22: WCDMA Idle Mode Behaviour Huawei
Page 23: WCDMA Idle Mode Behaviour Huawei

Cell Reselection• If GSM cell is ranked as the best cell, the UE shall reselect that GSM cell.

• If a WCDMA cell is ranked as the best cell and the quality measure for cell selection and reselection is set to CPICH RSCP(QualMeas = CPICH_RSCP), the UE shall reselect that UTRAN cell.

• If a WCDMA cell is ranked as the best cell and the quality measure for cell selection and reselection is set to CPICH Ec/N0(QualMeas = CPICH_ECNO), the UE shall perform a second ranking of the UTRAN cells according to the R criteria specified above.

• The new cell is better ranked than the serving cell during a time interval Treselections (treSelection)

Page 24: WCDMA Idle Mode Behaviour Huawei

Location Registration

• Location registration is used for the PLMN to trace the current status of the UE. Location registration ensures that the UE is connected to the network when the UE does not perform any operation for a long period.

Location registration is of the following three types:• Normal location registration• Periodic location registration• IMSI attach/detach

Page 25: WCDMA Idle Mode Behaviour Huawei

Normal Location Registration

• The UE performs normal location registration in the following conditions:

• After the switch-on, the UE selects a suitable cell that belongs to a new LA or RA. That is,the LA or RA is different from that recorded in the USIM before the switch-off of the UE.

• The UE in idle mode enters the cell of a new LA or RA.

Page 26: WCDMA Idle Mode Behaviour Huawei

Periodic Location Registration• Periodic location registration may be used to periodically

notify the network of the availability of the UE.

• It is controlled by a Periodic Location Update timer T3212or a Periodic Routing Area Update timer T3312.

• The value of T3212 is sent by the network to the UE in SIB 1. The value of T3312 is sent by the network to the UE in the messages ATTACH ACCEPT and ROUTING AREA UPDATE ACCEPT. The value of T3312 shall be unique within an RA.

Page 27: WCDMA Idle Mode Behaviour Huawei

IMSI Attach/Detach• A location registration request indicating IMSI attach is made

when the UE is activated in the same LA in which it was deactivated

• It is managed by the cell parameter att sent on the BCCH. If the parameter att is set to 1, the UE sends an “attach” or “detach”.

• When the UE is switched on and the IMSI attach/detach procedure is applied, the UE performs a location registration request, indicating IMSI attach, if it is in the same LA or RA in which it was switched off. If the registration area is changed, a normal LA update is performed by the UE.

Page 28: WCDMA Idle Mode Behaviour Huawei

Paging Reception• When a UE stays in idle mode, the paging to the UE is

performed within an LA or RA or the whole RNC. The UE reads the paging information from the PICH and S-CCPCH. The PICH indicates when the UE reads the paging information from the S-CCPCH, whereas the S-CCPCH carries specific paging messages.

• To reduce power consumption, the UE can read the information from the PICH only at a particular time. This is known as the Discontinuous Reception (DRX) technology. The interval between two consecutive periods of time is called DRX cycle.

Page 29: WCDMA Idle Mode Behaviour Huawei

• DRX cycle length shall be 2^k frames, where k is an integer and is decided by the following three parameters:

• CN domain specific DRX cycle length for CS=DRXCYCLELENCOEF• CN domain specific DRX cycle length for PS• UTRAN DRX cycle length=MaccPageRepeatTimes

Page 30: WCDMA Idle Mode Behaviour Huawei

System Information Reception• The structure of system information is like a tree, which includes the following

items:• MIB Master Information Block (MIB) provides reference and scheduling

information for a number of SIBs in a cell or one or two Scheduling Blocks (SBs) in a cell. The MIB contains only the PLMN types supported and the corresponding PLMN identities.

• SB Scheduling Block (SB) provides reference and scheduling information for

other SIBs. The scheduling information of an SIB may be included in the MIB or SB.

• SIBSystem Information Block (SIB) contains actual system information. It consists of system information elements (IEs) with the same purpose.

Page 31: WCDMA Idle Mode Behaviour Huawei

System Information

Page 32: WCDMA Idle Mode Behaviour Huawei

Reception of System Information The UE shall read system information broadcast on a BCH transport channel when

the UE is in idle mode or connected. Then, the UE takes actions on the following occasions:

• When the UE is switched off Except the SIBs stored in the USIM and used for the stored information cell selection, the UE shall consider other stored SIBs as invalid.

• When the UE is switched on The UE shall store SIBs with an area scope (cell, PLMN, or equivalent PLMN) and their value tag. These SIBs are used when the UE returns to the cells.

• When the UE selects a new cell in a new PLMN The UE shall consider all current SIBs with an area scope (cell or PLMN) as invalid, and shall store and use a new SIB.

• When the UE selects a new cell in the current PLMN The UE shall consider all current SIBs with an area scope (cell) as invalid, and shall store and use a new SIB


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